08-03-2025
Engineers build 30-feet-long all-glass bridge using 6,000-year-old technique
Architect and structural engineer Masoud Akbarzadeh has challenged conventional wisdom by constructing a bridge from a material deemed unsuitable: glass.
The architect has created a 30-foot-long bridge built entirely of interlocking 16-millimeter (0.63 inches) hollow glass pieces. It looks incredibly fragile and beautiful, like a shimmering, light-filled, translucent structure.
"All these pieces alone, hollow glass units, might seem quite brittle—and they are, but depending on how you design to put these glass units together, they start relying on each other, and the units' assembly establishes a path for the load to be transferred efficiently. Thus, the bridge gains strength as a whole," said Akbarzadeh, an associate professor of architecture at the Weitzman School of Design.
Over three weeks in 2024, the team constructed this final structure, dubbed 'Glass Bridge: The Penn Monument for Hope.'
The journey to create this masterpiece was anything but simple. It took six years of planning, drafting, and revising.
The bridge draws on millennia-old engineering and architectural principles, particularly those associated with funicular design. This means the bridge is built to naturally handle forces, primarily using compression (pushing forces) to stay strong and stable.
This concept, focused on balancing forces through arches and vaults, was employed as far back as 4000 BCE by the Mesopotamians and later by the Romans in their iconic structures.
The first step was a modest but crucial 10-foot prototype, a proving ground for their digital machinations. The bridge prototype used hollow glass units, which interlocked to form the bridge's arch. A major challenge was finding a way to connect the glass pieces without causing them to crack.
Eventually, structural double-sided VHB tape and precision-cut acrylic connectors were used. Acrylic connectors joined the glass units, ensuring accurate alignment and load transfer.
In stress testing, this prototype glass unit successfully withstood a significant amount of compressive force (41.6 kilopounds).
"This approach permitted the necessary tolerance and ease of assembly without compromising the integrity of the glass," said Yao Lu, a core member of the design team.
Villanova University helped the team find a material to prevent glass pieces from cracking when they are touched. They discovered that polyvinyl butyral (PVB), commonly used in safety glass, worked perfectly as an interface material.
This laminate material acted as a buffer between glass modules, preventing direct contact and stress concentrations.
Building the glass bridge required far greater precision than a standard bridge.
The steel or concrete may allow for slight imperfections, but the glass units had to fit together with near-perfect accuracy — with a tolerance of only 0.1 millimeters. This incredibly tight margin of error made the construction extremely challenging.
"But with these connectors, every cut, every angle, every dimension had to be accurate within 0.1 millimeters," Akbarzadeh said.
"When you're dealing with 124 separate glass units, even the tiniest misalignment can multiply across the entire span. If we didn't maintain that level of precision, the whole structure could have collapsed under its own weight," he added in the press release.
To reach the required precision, the team partnered with firms located in Germany and China.
On November 30th, after a week of long days and late nights, the bridge stood tall.
The Glass Bridge is currently on exhibit at the Corning Museum of Glass until September 1st. Before the exhibit opened, Greenhouse Media filmed the bridge's construction and interviewed the team, creating a documentary about the project.
The bridge construction has been reported in the journal Engineering Structures.
